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Quantitative Elucidation Of A Distinct Spatial Gradient-Sensing Mechanism In Fibroblasts, Ian C. Schneider, Jason M. Haugh Dec 2005

Quantitative Elucidation Of A Distinct Spatial Gradient-Sensing Mechanism In Fibroblasts, Ian C. Schneider, Jason M. Haugh

Ian C. Schneider

Migration of eukaryotic cells toward a chemoattractant often relies on their ability to distinguish receptor-mediated signaling at different subcellular locations, a phenomenon known as spatial sensing. A prominent example that is seen during wound healing is fibroblast migration in platelet-derived growth factor (PDGF) gradients. As in the well-characterized chemotactic cells Dictyostelium discoideum and neutrophils, signaling to the cytoskeleton via the phosphoinositide 3-kinase pathway in fibroblasts is spatially polarized by a PDGF gradient; however, the sensitivity of this process and how it is regulated are unknown. Through a quantitative analysis of mathematical models and live cell total internal reflection fluorescence microscopy …


Synthesis And Characterization Of Highly Amine Functionalized Mesoporous Organosilicas By An “All-In-One” Approach, Rebecca Voss, Arne Thomas, Markus Antonietti, Geoffrey A. Ozin Aug 2005

Synthesis And Characterization Of Highly Amine Functionalized Mesoporous Organosilicas By An “All-In-One” Approach, Rebecca Voss, Arne Thomas, Markus Antonietti, Geoffrey A. Ozin

Rebecca Cademartiri

Mesoporous organosilicas (MOs) represent a promising class of organic–inorganic nanocomposites for a broad range of applications like catalysis, sensing, separation, or microelectronics. Their distinct feature is the presence of organic groups incorporated into the channel walls of a mesoporous structure. Here, we present a convenient “all-in-one” approach using silsesquioxane surfactant precursors for the functionalization of the channel walls with primary amine groups. The monomer is made by a hydroboration/aminolysis sequence on the base of a commercial monomer, with the template bound to the functionalization site by hydroboration and released after silica condensation and aminolysis. This combination ensures both the placement …


Spatial Analysis Of 3′ Phosphoinositide Signaling In Living Fibroblasts, Iii: Influence Of Cell Morphology And Morphological Polarity, Ian C. Schneider, Elizabeth M. Parrish, Jason M. Haugh Aug 2005

Spatial Analysis Of 3′ Phosphoinositide Signaling In Living Fibroblasts, Iii: Influence Of Cell Morphology And Morphological Polarity, Ian C. Schneider, Elizabeth M. Parrish, Jason M. Haugh

Ian C. Schneider

Activation of phosphoinositide (PI) 3-kinase is a required signaling pathway in fibroblast migration directed by platelet-derived growth factor. The pattern of 3′ PI lipids in the plasma membrane, integrating local Pl 3-kinase activity as well as 3′ PI diffusion and turnover, influences the spatiotemporal regulation of the cytoskeleton. In fibroblasts stimulated uniformly with platelet-derived growth factor, visualized using total internal reflection fluorescence microscopy, we consistently observed localized regions with significantly higher or lower 3′ PI levels than adjacent regions (hot and cold spots, respectively). A typical cell contained multiple hot spots, coinciding with apparent leading edge structures, and at most …


Elastic Waves Push Organic Fluids From Reservoir Rock, Igor A. Beresnev, R. Dennis Vigil, Wenqing Li, Wayne D. Pennington, Roger M. Turpening, Pavel P. Iassonov, Robert P. Ewing Jul 2005

Elastic Waves Push Organic Fluids From Reservoir Rock, Igor A. Beresnev, R. Dennis Vigil, Wenqing Li, Wayne D. Pennington, Roger M. Turpening, Pavel P. Iassonov, Robert P. Ewing

R. Dennis Vigil

Elastic waves have been observed to increase productivity of oil wells, although the reason for the vibratory mobilization of the residual organic fluids has remained unclear. Residual oil is entrapped as ganglia in pore constrictions because of resisting capillary forces. An external pressure gradient exceeding an ‘‘unplugging’’ threshold is needed to carry the ganglia through. The vibrations help overcome this resistance by adding an oscillatory inertial forcing to the external gradient; when the vibratory forcing acts along the gradient and the threshold is exceeded, instant ‘‘unplugging’’ occurs. The mobilization effect is proportional to the amplitude and inversely proportional to the …


Temperature Dependence Of Order, Disorder, And Defects In Laterally Confined Diblock Copolymer Cylinder Monolayers, Matthew R. Hammond, Eric W. Cochran, Glenn H. Fredrickson, Edward J. Kramer Jul 2005

Temperature Dependence Of Order, Disorder, And Defects In Laterally Confined Diblock Copolymer Cylinder Monolayers, Matthew R. Hammond, Eric W. Cochran, Glenn H. Fredrickson, Edward J. Kramer

Eric W. Cochran

Monolayer arrays of polystyrene-poly(2-vinylpyridine) diblock copolymer cylinders with excellent orientational order and a very low density of dislocations are prepared by cooling slowly from above the bulk order - disorder temperature (ODT) ∼212°C within silicon oxide channels one cylinder spacing a in depth and 2 μm in width. The translational order of this array, however, is short range with a correlation length of ∼12a. If such an array is heated to a temperature above the glass transition temperature of the block copolymer (100°C) but well below the ODT, a finite density of thermally generated dislocations is observed, which leads to …


Inorganic Supramolecular Host Architectures:  [(M@18c6)2][Tli4]·2h2o, M = 0.5 Tl, (Nh4,Nh3), (H3o,H2o), Franziska Rieger, Anja V. Mudring Jan 2005

Inorganic Supramolecular Host Architectures:  [(M@18c6)2][Tli4]·2h2o, M = 0.5 Tl, (Nh4,Nh3), (H3o,H2o), Franziska Rieger, Anja V. Mudring

Anja V. Mudring

The compounds [(M@18c6)2][TlI4]·2H2O, M = Tl, (NH4,NH3), (H3O,H2O) (cubic, Fd3̄; a = 1481.00 pm, for M = 0.5 Tl, a = 1304.65 pm for M = (NH4,NH3), a = 1313.67 pm for M = (H3O,H2O)) can be obtained from solution in the presence of traces of transition metal halides (like copper and mercury halides). Apparently the transition metal cations work as a template in the form of tetrahedral [MX4] units during the synthesis of the supramolecular host architecture. That the compounds are versatile host lattices for tetrahedrally coordinated transition metal units becomes obvious by the large group of known host−guest …


The Quadrupole Moment Of The 3/2+ Nuclear Ground State Of Au197 From Electric Field Gradient Relativistic Coupled Cluster And Density-Functional Theory Of Small Molecules And The Solid State, Peter Schwerdtfeger, Radovan Bast, Michael C.L. Gerry, Christoph R. Jacobs, Martin Jansen, Vladimir Kello, Anja V. Mudring, Andrzej J. Sadlej, Trond Saue, Tilo Sohnel, Friedrich E. Wagner Jan 2005

The Quadrupole Moment Of The 3/2+ Nuclear Ground State Of Au197 From Electric Field Gradient Relativistic Coupled Cluster And Density-Functional Theory Of Small Molecules And The Solid State, Peter Schwerdtfeger, Radovan Bast, Michael C.L. Gerry, Christoph R. Jacobs, Martin Jansen, Vladimir Kello, Anja V. Mudring, Andrzej J. Sadlej, Trond Saue, Tilo Sohnel, Friedrich E. Wagner

Anja V. Mudring

An attempt is made to improve the currently accepted muonic value for the Au197 nuclear quadrupole moment [+0.547(16)×10−28m2] for the 3/2+ nuclear ground state obtained by Powers et al. [Nucl. Phys.A230, 413 (1974)]. From both measured Mössbauer electric quadrupole splittings and solid-state density-functional calculations for a large number of gold compounds a nuclear quadrupole moment of +0.60×10−28m2 is obtained. Recent Fourier transform microwave measurements for gas-phase AuF, AuCl, AuBr, and AuI give accurate bond distances and nuclear quadrupole coupling constants for the Au197isotope. However, four-component relativistic density-functional calculations for these molecules yield unreliable results for the Au197 nuclear quadrupole moment. …


Rare-Earth Iodides In Ionic Liquids:  The Crystal Structure Of [Set3]3[Lni6] (Ln = Nd, Sm), Anja V. Mudring, Arash Babai Jan 2005

Rare-Earth Iodides In Ionic Liquids:  The Crystal Structure Of [Set3]3[Lni6] (Ln = Nd, Sm), Anja V. Mudring, Arash Babai

Anja V. Mudring

Crystals of [SEt3]3[LnI6] (Ln = Nd, Sm) were obtained by the reaction of LnI2 with the ionic liquid [SEt3][Tf2N] [Tf2N = bis(trifluoromethanesulfonyl)imide]. The compounds are characterized by octahedral [LnI6]3- units that are surrounded by a distorted cube of triethylsulfonium cations.


Anhydrous Praseodymium Salts In The Ionic Liquid [Bmpyr][Tf2n]:  Structural And Optical Properties Of [Bmpyr]4[Pri6][Tf2n] And [Bmyr]2[Pr(Tf2n)5], Arash Babai, Anja V. Mudring Jan 2005

Anhydrous Praseodymium Salts In The Ionic Liquid [Bmpyr][Tf2n]:  Structural And Optical Properties Of [Bmpyr]4[Pri6][Tf2n] And [Bmyr]2[Pr(Tf2n)5], Arash Babai, Anja V. Mudring

Anja V. Mudring

Purposely designed ionic liquids can be excellent solvents for spectroscopic studies of rare earth compounds. Absorption and emission spectra of anhydrous PrI3 and Pr(Tf2N)3 in the ionic liquid 1,1-n-butyl-methylpyrrolidinium bis(trifluoromethanesulfonyl)amide, [bmpyr][Tf2N], at room temperature are presented together with the emission spectra of solid [bmpyr]2[Pr(Tf2N)5] and [bmpyr]4[PrI6][Tf2N]. After excitation into the 3P1 level, remarkable luminescence not only from the 1D2 level but also from the 3P0 and even from the 3P1 level is observed. Amazingly in the case of the solid compounds and even more astonishing for a solution of Pr(Tf2N)3 in [bmpyr][Tf2N] the strongest luminescence transitions start from the 3P0 …


Lone Pair Effect In Thallium(I) Macrocyclic Compounds, Anja V. Mudring, Franziska Rieger Jan 2005

Lone Pair Effect In Thallium(I) Macrocyclic Compounds, Anja V. Mudring, Franziska Rieger

Anja V. Mudring

The role of the inert (lone) pair of electrons in thallium(I) salts is studied by comparison of the compounds [Tl@18-crown-6]+X- (X = TlI4, ClO4) and [K@18-crown-6]+ClO4-. In contrast to common introductory chemistry textbook opinions, the paradigm that s−p hybridization is a prerequisite for an inert electron pair to become stereochemically active in compounds of the heavier main group elements has to be revised. Instead, an inert pair of electrons is expected to become stereochemically involved whenever it is forced to participate in antibonding orbital interactions with its surroundings, and there is the possibility for a structural distortion that minimizes these …